Collapsible umbrella structures are utilized for numerous purposes. One type of collapsible umbrella construction is that employed in connection with the fabrication of beach umbrellas. These umbrellas must withstand the corrosive effects of salt water and at the same time must be sufficiently strong to permit repeated and extended usage while resisting the effects of wind and harsh treatment. Another type of umbrella construction is that constituting a personal umbrella intended to be collapsed between an extended or stretched configuration and a collapsed or bundled configuration wherein the canopy and its supporting ribs come to rest surrounding and bundled around a supporting central rod or pole.
A number of umbrella constructions have been patented such as, for example, in U.S. Pat. Nos. 3,424,180; 3,844,301; 3,890,990; and 4,370,994.
In U.S. Pat. No. 3,424,180, G. Andolfi reveals a construction for an umbrella, beach sun shade or parasol which is completely made of a plastic material such as resin and fiber glass. The framework is alleged to be of very easy and ready assembly without the use of any metal parts thus resulting in a rust-proof structure. The composition is, moreover, stated to be considerably less weight than corresponding metal frameworks.
V. Harrell in U.S. Pat. No. 3,844,301 reveals a collapsible umbrella having a plastic frame consisting of dual U-shaped constructions. The frame includes an integral handle in which a control member is manually reciprocated for opening the associated canopy and retracting the same into the frame. It is disclosed that the frame includes a closure at both ends for protecting the folded canopy. The canopy is supported by a plurality of flexible ribs which are used to support the canopy in the configuration of a transparent plastic bubble. The ribs are molded from a flexible plastic material such a vinyl-chloride compound with controlled filler to obtain a desired flexibility.
U.S. Pat. No. 3,890,990 (J. Schafer) reveals a fastening arrangement for attaching a crown, a handle, and dome rib parts to a stick and dome rib respectively. The fastening arrangement includes an enlarged recess in a member to be attached to the stick or dome rib and a retaining member forced into the recess and locked in the recess so as to bite into the wall of the recess and into the surface of the stick or dome rib.
B. Pittman shows in U.S. Pat. No. 4,370,994 an inflatable umbrella provided in such a way as to be collapsible and so as to be retained in the form of a small, easily carried package when not in use. The construction can be rapidly inflated to an operative configuration by the user or by an air source. The umbrella comprises a flexible plastic cover sheet having a generally circular outline and undercarriage which includes a flexible plastic panel having a star-like configuration and elongate flexible plastic tubular member having a bulbous handle portion at the free end, and a valve arrangement mounted on the handle to permit air to be selectively blown into and released from the interior of the tubular member and enclosed air space. The star-like outline of the panel defines radiating spokes of the air space which extend to a point closely adjacent to the periphery of the cover sheet.
While the above constructions are generally satisfactory for the purposes intended, they are not suited generally for withstanding the abuse and hard handling to which such umbrella structures are usually subjected, nor are they susceptible to providing extended longevity and thus they do not anticipate the purpose of the present invention.